ARM: 5841/1: a driver for on-chip ETM and ETB

This driver implements support for on-chip Embedded Tracing Macrocell and
Embedded Trace Buffer. It allows to trigger tracing of kernel execution flow
and exporting trace output to userspace via character device and a sysrq
combo.

Trace output can then be decoded by a fairly simple open source tool [1]
which is already sufficient to get the idea of what the kernel is doing.

[1]: http://github.com/virtuoso/etm2human

Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig.debug

@@ -83,6 +83,14 @@ config DEBUG_ICEDCC
 	  It does include a timeout to ensure that the system does not
 	  totally freeze when there is nothing connected to read.
 
+config OC_ETM
+	bool "On-chip ETM and ETB"
+	select ARM_AMBA
+	help
+	  Enables the on-chip embedded trace macrocell and embedded trace
+	  buffer driver that will allow you to collect traces of the
+	  kernel code.
+
 config DEBUG_DC21285_PORT
 	bool "Kernel low-level debugging messages via footbridge serial port"
 	depends on DEBUG_LL && FOOTBRIDGE

arch/arm/include/asm/hardware/coresight.h

@@ -0,0 +1,165 @@
+/*
+ * linux/arch/arm/include/asm/hardware/coresight.h
+ *
+ * CoreSight components' registers
+ *
+ * Copyright (C) 2009 Nokia Corporation.
+ * Alexander Shishkin
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __ASM_HARDWARE_CORESIGHT_H
+#define __ASM_HARDWARE_CORESIGHT_H
+
+#define TRACER_ACCESSED_BIT	0
+#define TRACER_RUNNING_BIT	1
+#define TRACER_CYCLE_ACC_BIT	2
+#define TRACER_ACCESSED		BIT(TRACER_ACCESSED_BIT)
+#define TRACER_RUNNING		BIT(TRACER_RUNNING_BIT)
+#define TRACER_CYCLE_ACC	BIT(TRACER_CYCLE_ACC_BIT)
+
+struct tracectx {
+	unsigned int	etb_bufsz;
+	void __iomem	*etb_regs;
+	void __iomem	*etm_regs;
+	unsigned long	flags;
+	int		ncmppairs;
+	int		etm_portsz;
+	struct device	*dev;
+	struct clk	*emu_clk;
+	struct mutex	mutex;
+};
+
+#define TRACER_TIMEOUT 10000
+
+#define etm_writel(t, v, x) \
+	(__raw_writel((v), (t)->etm_regs + (x)))
+#define etm_readl(t, x) (__raw_readl((t)->etm_regs + (x)))
+
+/* CoreSight Management Registers */
+#define CSMR_LOCKACCESS 0xfb0
+#define CSMR_LOCKSTATUS 0xfb4
+#define CSMR_AUTHSTATUS 0xfb8
+#define CSMR_DEVID	0xfc8
+#define CSMR_DEVTYPE	0xfcc
+/* CoreSight Component Registers */
+#define CSCR_CLASS	0xff4
+
+#define CSCR_PRSR	0x314
+
+#define UNLOCK_MAGIC	0xc5acce55
+
+/* ETM control register, "ETM Architecture", 3.3.1 */
+#define ETMR_CTRL		0
+#define ETMCTRL_POWERDOWN	1
+#define ETMCTRL_PROGRAM		(1 << 10)
+#define ETMCTRL_PORTSEL		(1 << 11)
+#define ETMCTRL_DO_CONTEXTID	(3 << 14)
+#define ETMCTRL_PORTMASK1	(7 << 4)
+#define ETMCTRL_PORTMASK2	(1 << 21)
+#define ETMCTRL_PORTMASK	(ETMCTRL_PORTMASK1 | ETMCTRL_PORTMASK2)
+#define ETMCTRL_PORTSIZE(x) ((((x) & 7) << 4) | (!!((x) & 8)) << 21)
+#define ETMCTRL_DO_CPRT		(1 << 1)
+#define ETMCTRL_DATAMASK	(3 << 2)
+#define ETMCTRL_DATA_DO_DATA	(1 << 2)
+#define ETMCTRL_DATA_DO_ADDR	(1 << 3)
+#define ETMCTRL_DATA_DO_BOTH	(ETMCTRL_DATA_DO_DATA | ETMCTRL_DATA_DO_ADDR)
+#define ETMCTRL_BRANCH_OUTPUT	(1 << 8)
+#define ETMCTRL_CYCLEACCURATE	(1 << 12)
+
+/* ETM configuration code register */
+#define ETMR_CONFCODE		(0x04)
+
+/* ETM trace start/stop resource control register */
+#define ETMR_TRACESSCTRL	(0x18)
+
+/* ETM trigger event register */
+#define ETMR_TRIGEVT		(0x08)
+
+/* address access type register bits, "ETM architecture",
+ * table 3-27 */
+/* - access type */
+#define ETMAAT_IFETCH		0
+#define ETMAAT_IEXEC		1
+#define ETMAAT_IEXECPASS	2
+#define ETMAAT_IEXECFAIL	3
+#define ETMAAT_DLOADSTORE	4
+#define ETMAAT_DLOAD		5
+#define ETMAAT_DSTORE		6
+/* - comparison access size */
+#define ETMAAT_JAVA		(0 << 3)
+#define ETMAAT_THUMB		(1 << 3)
+#define ETMAAT_ARM		(3 << 3)
+/* - data value comparison control */
+#define ETMAAT_NOVALCMP		(0 << 5)
+#define ETMAAT_VALMATCH		(1 << 5)
+#define ETMAAT_VALNOMATCH	(3 << 5)
+/* - exact match */
+#define ETMAAT_EXACTMATCH	(1 << 7)
+/* - context id comparator control */
+#define ETMAAT_IGNCONTEXTID	(0 << 8)
+#define ETMAAT_VALUE1		(1 << 8)
+#define ETMAAT_VALUE2		(2 << 8)
+#define ETMAAT_VALUE3		(3 << 8)
+/* - security level control */
+#define ETMAAT_IGNSECURITY	(0 << 10)
+#define ETMAAT_NSONLY		(1 << 10)
+#define ETMAAT_SONLY		(2 << 10)
+
+#define ETMR_COMP_VAL(x)	(0x40 + (x) * 4)
+#define ETMR_COMP_ACC_TYPE(x)	(0x80 + (x) * 4)
+
+/* ETM status register, "ETM Architecture", 3.3.2 */
+#define ETMR_STATUS		(0x10)
+#define ETMST_OVERFLOW		(1 << 0)
+#define ETMST_PROGBIT		(1 << 1)
+#define ETMST_STARTSTOP		(1 << 2)
+#define ETMST_TRIGGER		(1 << 3)
+
+#define etm_progbit(t)		(etm_readl((t), ETMR_STATUS) & ETMST_PROGBIT)
+#define etm_started(t)		(etm_readl((t), ETMR_STATUS) & ETMST_STARTSTOP)
+#define etm_triggered(t)	(etm_readl((t), ETMR_STATUS) & ETMST_TRIGGER)
+
+#define ETMR_TRACEENCTRL2	0x1c
+#define ETMR_TRACEENCTRL	0x24
+#define ETMTE_INCLEXCL		(1 << 24)
+#define ETMR_TRACEENEVT		0x20
+#define ETMCTRL_OPTS		(ETMCTRL_DO_CPRT | \
+				ETMCTRL_DATA_DO_ADDR | \
+				ETMCTRL_BRANCH_OUTPUT | \
+				ETMCTRL_DO_CONTEXTID)
+
+/* ETB registers, "CoreSight Components TRM", 9.3 */
+#define ETBR_DEPTH		0x04
+#define ETBR_STATUS		0x0c
+#define ETBR_READMEM		0x10
+#define ETBR_READADDR		0x14
+#define ETBR_WRITEADDR		0x18
+#define ETBR_TRIGGERCOUNT	0x1c
+#define ETBR_CTRL		0x20
+#define ETBR_FORMATTERCTRL	0x304
+#define ETBFF_ENFTC		1
+#define ETBFF_ENFCONT		(1 << 1)
+#define ETBFF_FONFLIN		(1 << 4)
+#define ETBFF_MANUAL_FLUSH	(1 << 6)
+#define ETBFF_TRIGIN		(1 << 8)
+#define ETBFF_TRIGEVT		(1 << 9)
+#define ETBFF_TRIGFL		(1 << 10)
+
+#define etb_writel(t, v, x) \
+	(__raw_writel((v), (t)->etb_regs + (x)))
+#define etb_readl(t, x) (__raw_readl((t)->etb_regs + (x)))
+
+#define etm_lock(t) do { etm_writel((t), 0, CSMR_LOCKACCESS); } while (0)
+#define etm_unlock(t) \
+	do { etm_writel((t), UNLOCK_MAGIC, CSMR_LOCKACCESS); } while (0)
+
+#define etb_lock(t) do { etb_writel((t), 0, CSMR_LOCKACCESS); } while (0)
+#define etb_unlock(t) \
+	do { etb_writel((t), UNLOCK_MAGIC, CSMR_LOCKACCESS); } while (0)
+
+#endif /* __ASM_HARDWARE_CORESIGHT_H */
+

arch/arm/kernel/Makefile

@@ -17,6 +17,8 @@ obj-y		:= compat.o elf.o entry-armv.o entry-common.o irq.o \
 		   process.o ptrace.o return_address.o setup.o signal.o \
 		   sys_arm.o stacktrace.o time.o traps.o
 
+obj-$(CONFIG_OC_ETM)		+= etm.o
+
 obj-$(CONFIG_ISA_DMA_API)	+= dma.o
 obj-$(CONFIG_ARCH_ACORN)	+= ecard.o 
 obj-$(CONFIG_FIQ)		+= fiq.o